For many years now, technologies have been developed and used to rehabilitate damaged water and sewage conduits. The various technologies basically consist of re-lining the inside walls of existing underground conduits to rehabilitate the underground conduits.
The service entrances of the existing conduit are initially plugged with a water plug carrying a position marker with a plug setting robot controlled by an operator looking through a video camera connected to the plug setting robot. Thereafter the existing conduit is re-lined internally with a flexible tubular liner impregnated with a curable resin which is cured in place with recirculating heated water after insertion in the underground conduit. Once the resin is cured and the re-lining of the existing conduit is done, the water plug can be located with a detection and drilling robot using the position marker of the water plug. Once the center of the water plug is located, the water plug is drilled out using a drill mounted on the robot which is operated by the operator.
The drill mounted on the robot typically consists of a main housing attached to the front portion of the robot that includes a power unit and an actuator for controlling a drilling head positioned at the front of the main housing. The drilling head includes a drill bit extending perpendicular to the drilling head and to the longitudinal axis of the underground conduit. The drilling head is rotatable about the longitudinal axis and also movable back and forth along the same axis such that the operator is able to precisely align the drill bit with the position marker of the water plug blocking the service entrances that may be located in any position around the circumference of the underground conduit. The drilling head is also movable along an axis perpendicular to the main housing such that when the drill bit is properly aligned with the service entrances, the rotating drill bit is actuated to move against the water plug and drill it out by moving the drilling head along that perpendicular axis. The drill head is then retracted thereby opening the previously plugged service entrance.
Problems may arise when during the re-lining process, the curable resin of the tubular liner seeps into the service entrance, cures inside the services entrance deeper than required such that the standard drill bit is not long enough to remove the cured resin and the services entrance remains blocked or partially clogged by cured resin. The length of the drill bit adapted to be mounted onto a drilling head as previously described is limited by the space available inside the underground conduit and it is not possible to install a longer drill bit onto the drilling head to remove resin cured deep inside the service entrance. The depth of insertion of the drill bit inside the service entrance is limited by the maximum extension of the drilling head along the perpendicular axis previously described.
Thus, when resin has seeped deep into the service entrance and the standard drilling system is unable to drill deep enough inside the service entrance, the service entrance remains plugged or partially plugged by the cured resin and the fluid connection cannot be re-established leaving the residence or business to which that particular service entrance is connected without water supply or with limited flow of water which is obviously unacceptable. The only solution is to dig up the ground to reach and replace that particular service entrance at great cost.
Therefore, there is a need for a drilling apparatus adapted to extend deeper and farther inside a plugged service entrance than prior art drilling apparatus.